THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.

[16:00:15]

JAKE TAPPER, CNN HOST: Donald Trump's domination dividing the GOP.

THE LEAD starts right now.

Breaking news in the race for 2016. We're told that Mitt Romney has something major to say about the state of his party, after Donald Trump had a pretty Super Tuesday.

It could be the moment when the war against ISIS shifted. That's the Pentagon's hope, anyway, American commandos on the ground capturing their first ISIS operative. Whom could that operative be giving up right now?

Plus, breaking news, a major discovery in the search for missing Flight 370. What exactly washed up on shore? And what can it tell us?

Good afternoon, everyone. Welcome to THE LEAD. I'm Jake Tapper.

Some major developments in politics just in the last couple of hours. First, 2012 Republican presidential nominee Mitt Romney announcing he is going to give a major speech tomorrow. It's what is anticipated something of a last-ditch attempt by the Republican establishment to try and stop Donald Trump's march to the nomination.

Second, one of the remaining five Republican candidates, Dr. Ben Carson, just announced he doesn't see a political path forward for his campaign. He's not going to attend tomorrow night's Republican debate. For the four Republicans who will be on the stage, a rapid- fire primary and caucus schedule in the next few days.

Four states vote Saturday, four more Tuesday, and CNN will host a debate with all the Republican candidates left in the key state of Florida a week from tomorrow, next Thursday night.

CNN political reporter Sara Murray is live just outside Miami in Singer Island, Florida.

Sara, this is really interesting. Trump won seven states last night. Ted Cruz won three. But the delegate count is much closer than that. Trump got 250 delegates last night. Cruz got 213. SARA MURRAY, CNN NATIONAL POLITICAL CORRESPONDENT: That's right,

Jake. But there is no doubt that Donald Trump was the clear winner coming out of last night and that he appears to be marching toward the Republican nomination.

Meanwhile, the Republican establishment is still pushing sharp opposition to the idea of Donald Trump as the nominee.

(BEGIN VIDEOTAPE)

MURRAY (voice-over): Riding high on a string of seven Super Tuesday wins...

DONALD TRUMP (R), PRESIDENTIAL CANDIDATE: I feel awfully good.

MURRAY: ... Donald Trump, now with a wide lead in the delegate fight, may be on the cusp of locking down the Republican nomination.

TRUMP: It's only too bad that winner didn't take all, because, if winner took all, this thing is over. We're just having a celebration.

MURRAY: As he steels himself for a potential general election fight.

TRUMP: Look, I am a unifier. I know a lot of people are going to find that a little hard to believe, but, believe me, I'm a unifier. Once we get all of this finished, I'm going to go after one person. That's Hillary Clinton.

MURRAY: Trump is vowing to cut deals and work more closely with the Washington establishment than President Obama.

TRUMP: Does he ever go and deal with Congress anymore? Does he ever speak to the Senate?

MURRAY: But the establishment isn't having it.

REP. BOB DOLD (R), ILLINOIS: I will not support Donald Trump now and I will not support him should he move on.

MURRAY: Republican leaders are still hoping someone can mount a challenge, as some suggest Ted Cruz, who won three states last night, could be the Trump alternative.

SEN. LINDSEY GRAHAM (R), SOUTH CAROLINA: I'm anybody but Trump. Ted and I are in the same party. Donald Trump is an interloper. I don't trust him.

MURRAY: And Ohio Governor John Kasich faces increasing pressure to step aside, including from supporters of Marco Rubio.

SEN. CORY GARDNER (R), COLORADO: There's no honorable mention in the nomination. John Kasich has run a good race and he will continue to run a good race, but there's no path to victory for him.

MURRAY: The field does appear to be winnowing. Today, Dr. Ben Carson put out a statement saying: "I don't see a political path forward," adding he will not attend Thursday's debate.

While Rubio, trailing Trump and Cruz in the delegate fight, still insists there's time for a comeback.

SEN. MARCO RUBIO (R-FL), PRESIDENTIAL CANDIDATE: Usually, in race like this, you have a front-runner. And at this point people would be saying you need to drop out and rally around the front-runner for the sake of the party. They're saying the opposite now. There will never come a time in this race where our supporters are asking us to get out and rally around Donald Trump.

MURRAY: All as Trump takes aim at the Florida senator.

TRUMP: I know it was a very tough night for Marco Rubio. He had a tough night.

MURRAY: Hoping to finish Rubio off right here in his home state.

TRUMP: But you know what? We're going to go to Florida. We're going to spend so much time in Florida.

(END VIDEOTAPE)

MURRAY: Jake, we're hearing a lot of blame game going on right now. Rubio supporters who want Kasich to get out. Cruz supporters who want to get Rubio out.

At the end of the day, it looks like all of these folks want to fight until the finish. They will have to find a way to win on their own -- Jake.

TAPPER: Sara Murray, thank you so much.

Many Republicans in Congress have grave concerns about Donald Trump as their nominee. This week, they are starting to go public.

Joining me now is Republican Congressman Scott Rigell of Virginia, who is warning that a Trump nomination would be nothing short of catastrophic.

[16:05:14]

Congressman, thanks for joining me. Really appreciate it.

REP. SCOTT RIGELL (R), VIRGINIA: Thank you, Jake.

TAPPER: You have called Trump a reckless, dangerous bully with a void in his heart.

But, Congressman, he keeps winning, including in your home Commonwealth of Virginia last night. Is it possible that your quarrel is not with Donald Trump, but with Republican voters?

RIGELL: Not at all.

I believe that Republican voters have got a reason to be upset and angry, but I'm submitting to them that the solution is not Donald Trump in any respect. And if I look at who would be our commander in chief, I represent a district that has the highest number of men and women in uniform of all the 435 congressional districts.

And to think that we would put our young men and women under the command of like someone Donald Trump, who is so reckless in what he said in foreign policy and so devoid of judgment, I cannot in good conscience vote for him. And I will not.

TAPPER: You will not vote for him. What are you going to do if he's the nominee?

RIGELL: Well, I'm not going to vote for Hillary Clinton.

I'm going to have to go in there and for the first time in my life write in someone. This is deeply troubling to me that I'm even here and having to talk about this topic. I didn't think I would see the day, but in this extremist moment that we're in, in our country, the solution is not Donald Trump.

When a person is seeking the highest office of the land, and the party that I have been a part of all my life and that I love, and yet he says he admires Putin, he quotes Mussolini, he can't get his way out of a KKK David Duke reference, he struggles with this, what is missing in the mind of a person who doesn't just immediately reject the KKK and David Duke?

He doesn't represent who we are as the Republican Party.

TAPPER: Do you think that the party needs to coalesce around an alternative, one person, instead of four?

RIGELL: Well, certainly. Now, in all full -- full candor, I'm a Marco Rubio fan. I have been. I'm all in for Marco.

But any of the other candidates, I believe, would unify us. And that's why when I sent my letter out to Virginia Republicans, I was very deliberate in not -- I didn't mention Marco, because I didn't want them to think this was about me pushing Marco. It was about me with my best judgment, as a businessman, as a father, husband, and a public servant for just five years, everything that I have learned in life says that Donald Trump is -- he really would harm -- I truly believe he would harm our country.

And I have got to speak out about this. And I am.

TAPPER: Are more members of Congress going to be speaking out?

RIGELL: Well, I just saw another friend up there on the monitor speaking out. And I appreciate Bob Dold doing this. And I get stopped in the hallways and all kind of places over there at the Capitol and they're going to, Scott, thank you for what you're doing.

Joining me now, CNN political commentator Mary Katharine Ham, Neera Tanden, president of the Center for American Progress, and in New York Kayleigh McEnany.

Kayleigh, let me start with you.

As a Trump supporter, if you look hard enough, you can say that the never Trump movement had a good night. Trump lost four states, even if Donald Trump won seven. You just heard the congressman. Are you concerned at all about this anyone but Trump movement?

KAYLEIGH MCENANY, DONALD TRUMP SUPPORTER: I'm not concerned, because you know what? The men who have stood besides Trump, two of them have really embraced him.

Chris Christie, who stood alongside him and sparred with Donald Trump, has come out and endorsed him. Mike Huckabee, today, came out and said it's time for people to get behind Donald Trump. He called it a peaceful revolution. And Mike Huckabee, I think, has really been on to something since long before this, since 2008, since 2010.

He said there is a strain in the Republican Party of elitism, of a country club mentality that rejects candidates like Christine O'Donnell and Sarah Palin and Donald Trump and Mike Huckabee.

The Republican Party, for the last eight years, and probably before that, has been picking winners and losers. But as Mike Huckabee said today, fortunately, we have an election. This isn't a decision of the Republican establishment. This is a decision of the American people.

Last night, the American people spoke. Donald Trump won seven states. He won the three states before this election. And I think that he will go on to win the nomination. And there's nothing the establishment can do about it. It's the American people's turn to speak and they're angry.

TAPPER: Mary Katharine, you're a Republican voter in Virginia. You just heard congressman -- I have to say I have never seen anything like that. He was obviously very emotional.

But I don't see any way that the establishment can stop Donald Trump. Do you?

MARY KATHARINE HAM, CNN POLITICAL COMMENTATOR: Look, there are real concerns here. And that's why he was emotional.

TAPPER: I'm not faulting him for it.

HAM: There are many people -- I'm not saying you are.

There are many people for whom this is serious, and they're not necessarily establishment Republicans. They're conservatives. They're conservative activists who have a real problem with this.

But I do think we're at a point where mathematically the consolidation didn't happen early enough for them to beat Trump outright. The three of them can stay in and prevent Trump perhaps. And there's this movement that would encourage them to do just that.

[16:10:05]

But I do think you're reaching a point mathematically where this is tough. That being said, I don't want to take away from what Trump did last night. But it was much less he was expected to do. And those margins and those delegates do matter.

TAPPER: Neera, there was a report in "The New York Times" talking about how the Democrats in the Clinton campaign, a lot of people are really excited to face Donald Trump. They think he's going to be easy to beat.

Let me tell you, I do not think he's going to be easy to beat. I think he's going to be a formidable contender.

NEERA TANDEN, PRESIDENT, CENTER FOR AMERICAN PROGRESS: I agree with you.

TAPPER: Tell me about the Clinton campaign, what the feeling is there.

TANDEN: Well, look, I do think we still have a primary. We still have a primary that we are going to have plenty of states. Hillary has to focus on that. And she is.

We have states coming up this weekend and next week. You know, he's obviously had a remarkable ability to shape the Republican race, seeing things in the Republican race no one else saw. He's a formidable candidate.

Seeing, you know, how he deals with other Republicans is very different from how he's going to deal with other -- with a Democratic candidate who is tough and who will give back. She's done races in New York, where we have seen people like Rudy Giuliani who had similar tendencies to bully folks.

So, I think she's focused on this race that she's in right now. But she has a message that is very different. It's inclusive. It's inclusive of all Americans. And that has been her message throughout this campaign. That is an answer to Trump.

TAPPER: All right, Neera, Mary Katharine, Kayleigh, stick around. We are going to have much more with you all.

But, first, sticking with our politics lead, Hillary Clinton is looking down the road after her big wins on Super Tuesday. But after winning four states as well, is there a path forward for Senator Bernie Sanders? We will ask one congresswoman who gave up a leadership position in the Democratic National Committee in order to endorse Bernie Sanders.

Back after this.

(COMMERCIAL BREAK)

[16:15:38] TAPPER: Welcome back to THE LEAD.

Continuing with our politics lead. And a path to a Democratic nomination looks a little clearer for Hillary Clinton after dominating Super Tuesday with seven victories to Bernie Sanders. That put her delegate count at 1,074, compared to 426 for Senator Sanders. Without super delegates, her total is 606 delegates, still 200 measure Sanders.

Today, her campaign acknowledges Senator Bernie Sanders has a good chance of winning two upcoming contests but they also say that the math just isn't there for him to close the gap and capture and nomination.

CNN's Jeff Zeleny joining me now live in Miami. We're told it's primary in fewer that two weeks.

Jeff, Sanders is not giving up. Not taking the Clinton campaign's advice.

JEFF ZELENY, CNN SENIOR WASHINGTON CORRESPONDENT: In fact, far from it, Jake. He called last night an extraordinary night. And he took a jab at pundits today. He said, for anyone who's calling this race over for Clinton, he will win in a landslide. Now, a landslide might be a slight exaggeration, but he does say this -- for anyone who's calling for him to leave this race to look for the exits, he says, why should he?

(BEGIN VIDEOTAPE)

HILLARY CLINTON (D), PRESIDENTIAL CANDIDATE: I'm so delighted to be here with you in Florida.

ZELENY (voice-over): Hillary Clinton is eyeing the Florida primary, in just two weeks, as one of the key contests that could wind down the Democratic campaign.

Bernie Sanders path may be narrowing. But after winning four states Tuesday night, he said any talk of Clinton locking up the nomination is premature.

SEN. BERNIE SANDERS (I-VT), PRESIDENTIAL CANDIDATE : This is not a general election. It's not winner-take-all.

ZELENY: But the Democratic race is sounding more and more just like that -- a general election fight.

CLINTON: America never stopped being great. We have to make America whole. Fill in what has been hallowed out.

We have to make strong the broken places, restitch the bond of trust and respect across our country.

ZELENY: The patriotic cheers show that Donald Trump can fire Democrats, too. She didn't mention his name, but he's already invoking hers.

DONALD TRUMP (R), PRESIDENTIAL CANDIDATE: I watched Hillary's speech. She makes to make America whole again and I'm trying to figure out what is that all about.

ZELENY: Before any Clinton-Trump match takes shape, she has Sanders to contend with. He's pledging to stay in the race until the convention, with friendlier contests coming up in Kansas and Nebraska, Maine and Michigan.

The Clinton campaign released a memo today, saying its rival might win more states but it called it mathematically impossible for Sanders to catch up. It's a delicate dance for Clinton who eight years ago bristled at calls for her to step aside.

CLINTON: People say all the time, well, are you going to keep going? Well, yes, of course, I'm going to keep going.

(END VIDEOTAPE)

ZELENY: Now, most presidential candidates leave the race when they're out of support or out of money. And Sanders is out of neither.

So, Jake, we're about to enter a very busy stretch of this Democratic campaign here. There are contests throughout the weekend in Nebraska, in Kansas, in Maine, in Louisiana, and, of course, that CNN Democratic debate in Flint, Michigan, on Sunday. That is going to set the tone for the final two-week stretch, what could be the final two week stretch of this campaign.

But these next few days, keep an eye on Sanders -- Jake.

TAPPER: All right. Jeff Zeleny, thank you so much.

Joining me now is Congresswoman Tulsi Gabbard, Democrat of Hawaii. She recently left her post as vice chair of the Democratic National Committee so that she could endorse Senator Bernie Sanders for president.

Congresswoman Gabbard, thanks so much for being here.

So, the first question is, why now? Wouldn't it have made more sense to do this a few weeks ago?

REP. TULSI GABBARD (D), HAWAII: I took my responsibilities as vice chair of the DNC very seriously. And part of that is you've got to remain neutral in these presidential primaries and other Democratic primaries. And I tried my best from that position to be able to talk about these issues, but you and I have talked about before these issues of war and peace and on both Democrat and Republican ticket. What kind of qualifications do we as a country want in our next commander in chief? I've got very frustrated because that conversation just was not

happening. Candidates were not being pushed to answer for their records and their positions and strategies, which is why I took that step. The stakes are so high. I think it's important we have a commander in chief who can exercise good judgment and foresight, fight strongly against our enemies and those who threaten us, and stop these interventionist regime change wars that our country has been stuck in now for over a decade.

[16:20:12] TAPPER: So, is that really the crux of the matter, is that in your view Hillary Clinton as secretary of state and as senator supported too many interventions whether Libya or the war in Iraq? Is that really the main issue here?

GABBARD: It is the central issue. I think we can tell what kind of commander in chief we'll have in the future by looking at their records and what they have stood for and done in the past. And this is about the vote for the Iraq war and then-Senator Clinton really championing that. It is about her being the architect and major pusher in the administration for the overthrow of Gadhafi in Libya, which, you know, "The New York Times" laid out very clearly last weekend, what the consequences of that were.

You know, a failed state, chaos, loss of life, and now, ISIS, and al Qaeda have a stronghold in that country that they didn't have before, and now to the present day with Syria. This is something we're dealing with right now and that our next commander in chief will very likely have to deal with as well.

And the contrasts between Secretary Clinton and Senator Sanders on this are stark opposites. Secretary Clinton saying, yes, we need to get rid of Assad. Condemn other regime change and put in the so- called no-fly zone which will put us directly in conflict with Russia that has military aircraft in that area.

TAPPER: How do you respond to the criticism that you seem to think that strongmen are preferable to an intervention? That it's OK with you that Gadhafi or Assad stay in power? And, by the way, that is also the position of Donald Trump.

GABBARD: I can tell you from my own experience, from having been deployed to Iraq in 2005, of working in a medical unit where every single day, I saw the costs of war up close and personal. I lost some of my friends there. I saw what happens when our country takes this regime change policy to war. Taking our country and our men and women into war without thought and foresight for what the consequences truly are.

And secondly, does that serve our best interest? Does it serve the safety and security of the American people?

So, as we saw in Iraq, the argument for that war was Saddam Hussein, was getting rid of a bad guy. The same argument was made to get rid of Gadhafi in Libya. And the same argument is being made to get rid of Assad in Syria. But the argument for what is actually going to make us more safe and

secure nation? What will weaken our enemy and allow us to destroy them? Those questions are not being asked or answered. When you're talking about these regime change policies. And if you look at each of them, and each instance, Iraq, Libya, and Syria the Islamic terrorist groups have become stronger as a result of the regime change interventionist action rather than the opposite which actually should be our objective.

TAPPER: All right. Congresswoman Tulsi Gabbard, thanks so much for coming in. We appreciate it. We'll see you soon.

GABBARD: Thanks, Jake. Good to see you.

TAPPER: Hopefully, you'll come back and we'll talk about these issues.

This programming note, you can watch former Secretary of State Hillary Clinton and Senator Bernie Sanders make their pitches to voters at the next Democratic debate in Flint, Michigan. That will be Sunday night 8:00 p.m. Eastern, only here on CNN.

Sticking with our politics lead, members of the Republican establishment say Donald Trump is dividing the party. But could his Super Tuesday wins actually show that he's unifying the base? Our panel will answer that, next.

Plus, for the first time a U.S. Special Ops team captures an ISIS operative in a highly classified and dangerous mission. So, who is this detainee and what could American forces be possibly learning from him?

(COMMERCIAL BREAK)

[16:28:08] TAPPER: Welcome back to THE LEAD. I'm Jake Tapper.

Staying with our politics lead. The conventional way of looking at Donald Trump is to say he's beating a divided field. The other way of looking at the runaway Republican frontrunner he's winning in a way no modern Republican has ever done before. That divide between Republicans north and south of the Mason-Dixon Line that we normally see seems to have been undone by Trump.

Let's take it up with our panel, Mary Katherine Ham, Neera Tanden, and Kayleigh McEnany.

Let me start with you, Neera, because I do want to give you the opportunity to respond to the criticism of Hillary Clinton from Congresswoman Tulsi Gabbard, stepping down from her post at the DNC and endorsing Bernie Sanders.

NEERA TANDEN, HILLARY CLINTON SUPPORTER: Yes, and I have a lot of respect for Tulsi. I would say that I think our experience in the Middle East is one that is a very difficult region. And to just say that Hillary is sort of an interventionist like every other neocon is just inaccurate. I think our experience in Syria shows, it's a very complicated region.

Not acting also has a lot of factors. We're seeing huge challenges with refugees around the world.

So, it's a complicated region and that's actually why we need people with some degree of experience to take on these challenges. Not people who have no experience whatsoever.

TAPPER: All right. Kayleigh, I want to talk about the divisions going on in the Republican race right now. In all of the states where Republicans voted last night with the one exception of Vermont, there was record turnout, record turnout.

I imagine, Kayleigh, that you would say to Mary Katherine that means that Donald Trump is unifying the party and bringing in new voters in a way that no other candidate has or could.

KAYLEIGH MCENANY, CNN POLITICAL COMMENTATOR: Yes, I would say that, because here's the thing: we've been told repeatedly that Donald Trump has a ceiling. At first, it was 30 percent. Then it was 35, then 40 percent. And then all of a sudden it's edging on 50 percent.

Because we saw the CNN poll, the national poll come out just a few days ago showing Donald Trump commanding 49 percent of GOP support in a field of five people. The ceiling keeps getting raised and raised, and along with that we see the turn out, as you mentioned, greater in every state with the exception of Vermont. I mean, these are record turnouts. And I have to think that Donald Trump is driving that when you couple the turnout with the poll numbers that we're seeing.